Owing to the almost complete match between the electron densities of carbon and sulfur, the porous nanocomposites present in essence a two-phase system and the filling of the host material can be precisely followed by this method. The absolute scattering intensities normalized per unit of mass were corrected accounting for the scattering contribution of the turbostratic microstructure of carbon and amorphous sulfur. The analysis using the Porod parameter and the chord-length distribution (CLD) approach determined the specific surface areas and filling mechanism of the nanocomposite materials, respectively.

Thus, SAXS provides comprehensive characterization of the sulfur distribution in porous carbon and valuable information for a deeper understanding of cathode materials of lithium−sulfur batteries. Although the level of complexity already reached with these molecules is quite impressive, longer molecules, such as polymers, are more promising for obtaining mechanical movements over larger distances.

We believe that the present method thus leads to highly valuable information for a better understanding and engineering of the cathodes of lithium/sulfur batteries. Moreover, it provides the firm basis for an operando analysis of Li/S8 cells by SAXS.

Representation of the sulfur impregnation into the micro−mesoporous carbon.

Scattering curves of CMK-8 with 0, 20, 40, and 50 wt % sulfur loading (a), the inset shows the non-shifted data magnified around the Bragg peaks, and fits of the modified Porod law (b). Kratky plot of the pore scattering with corresponding CLD fit (c) and CLD (d). The inset shows the Porod length lP (black) and from the CLD fit (red).